The present invention in general relates to a technology applied in mobile terminals such as portable telephones and portable information equipments, or mobile communication control devices. This invention particularly relates to a technology which reduces the labor required for network management and control load relating to hand-over (switchover of containing radio base stations).
In recent years, with the explosive spread of mobile terminals, network control and management tend to become increasingly complicated. During hand-over for smoothly switching over containing radio base stations following the area movement of a mobile terminal, particularly, it is necessary to make equipment on the network cooperate with one another. Due to this, the problem of network control and management load appears. Means and methods for effectively solving this problem have been, therefore, demanded.
FIG. 9 is a block diagram that shows the constitution of a conventional mobile communication system. As shown in this figure, a fixed telephone 1 is installed in, for example, a company or house and serves as a terminal establishing voice-communication with a mobile terminal 10 to be described later or other fixed telephones through an external network 2. A switchboard 3 is contained in the external network 2 and switches over calls. A management server 4 manages positional information indicating the position (area) at which the mobile terminal 10 is present. A region main switchboard 5 is contained in a mobile communication network 6 and switches over calls.
A switchboard 71 is contained in the mobile communication network 6 and switches over mobile communication calls. This switchboard 71 contains radio base stations 81 and 82. The radio base station 81 establishes communication with the mobile terminal within an area 91 through a radio line. The radio base station 82 establishes communication with a mobile terminal within an area 92 adjacent the area 91 through a radio line.
A switchboard 72 is contained in the mobile communication network 6 and switches over mobile communication calls. This switchboard 72 contains radio base stations 83 and 84. The radio base station 83 establishes communication with the mobile terminal within an area 93 adjacent the area 92 through a radio line. The radio base station 84 establishes communication with the mobile terminal within an area 94 adjacent the area 93 through a radio line.
The mobile terminal 10 is a portable telephone or the like and establishes radio-communication with any one of the radio base stations 81 to 84 if the terminal 10 is located in any one of the areas 91 to 94. The mobile terminal 10 regularly informs the management server 4 of positional information. Here, in the areas 91 to 94 stated above, a multi-area method by which adjacent two areas are set to overlap each other is adopted. In the overlapping areas, therefore, the mobile terminal 10 informs the management server 4 of information on two positions.
With the above constitution, when the fixed telephone 1 calls the mobile terminal 10, the call from the fixed telephone 1 reaches the switchboard 3 through the external network 2. Accordingly, the switchboard 3 accesses the management server 4 and acquires positional information on the mobile terminal 10. In this case, it is assumed that the mobile terminal 10 is located in the area 91. Next, the switchboard 3 switches over the call to the regional main switchboard 5. Accordingly, a wire line is set in the route of the mobile communication network 6, the switchboard 71 and the radio base station 81 and further the mobile terminal 10 in the area 91 is called by the radio base station 81 through the radio line. When the mobile terminal 10 responds to the call, a line is established between the fixed telephone 1 and the mobile terminal 10.
Assumed that the mobile terminal 10 is moving from the area 91 to the area 92 while the communication line is being established. Namely, the mobile terminal 10 is located in a portion in which the areas 91 and 92 overlap each other. Therefore, the mobile terminal 10 informs the management server 4 of not only positional information corresponding to the area 91 but also that corresponding to the area 92 through the radio base station 82, the switchboard 71, the mobile communication network 6 and the regional main switchboard 5.
Here, if a reception field intensity corresponding to the radio base station 82 exceeds that corresponding to the radio base station 81, the mobile terminal 10 informs the radio base station 82 of a switchover request for switching over the containing radio base station from the radio base station 81 to the radio base station 82. Following this, the radio base station 82 informs the management server 4 of the switchover request by way of the switchboard 71, the mobile communication network 6 and the regional main switchboard 5.
The management server 4 notifies the switchboard 71 that the containing radio base station of the mobile terminal 10 should be switched over from the radio base station 81 to the radio base station 82. By doing so, information necessary for line control is transmitted from the radio base station 81 to the radio base station 82 through the switchboard 71. When receiving the information, the radio base station 82 establishes a radio line with the mobile terminal 10 in the area 92. Next, the radio base station 81 disconnects the radio line with the mobile terminal 10. In this way, the mutual cooperation among the switchboard 71, the radio base station 81, the radio base station 82 and the management server 4 conventionally allows smooth switchover (hand-over) from the radio base station 81 to the radio base station 82.
In the meantime, as already described above, during hand-over in mobile communications, control and management are required to make a plurality of equipment (the radio base station 81, the switchboard 71, the management server 4 and the like) at the wire network side cooperate with one another. However, during the hand-over, since it is necessary to communicate information among the equipment and to conduct complex control, great network management and control load is generated. Particularly, in circumstances where the number of operating mobile terminals increases rapidly, the network management and control load increases steadily, accordingly.
It is an object of the present invention to provide a method and system for mobile communication which reduces a work load of network control and management during hand-over. It is another object of this invention to provide a computer readable recording medium that stores a computer program which when executed realizes the method according to the present invention.
The mobile communication system according to the present invention comprises a management server which manages a fixed address of the mobile terminal and not less than one dynamic address dynamically allotted to the mobile terminal within not less than one service area and a host transmitting information with the fixed address used as a header. The mobile terminal notifies the management server of the dynamic address in a real time manner, and notifies, if stretching over at least two service areas, the management server of a first dynamic address and a second dynamic address corresponding to the at least two service areas. The management server transfers the information with the first dynamic address and the second dynamic address used as a header if the information is transmitted from the host and the first dynamic address and the second dynamic address are allotted to the mobile terminal.
Thus, if one or more dynamic addresses of the mobile terminal are managed unitarily by the management server in a real time manner, information is transmitted from the host and one or more dynamic addresses are allotted to the mobile terminal, then information is transferred while using the one or more dynamic addresses allotted at this moment as a header. Therefore, compared with a conventional case, it is possible to reduce network control and management load relating to hand-over.
Furthermore, if the mobile terminal stretches over at least two service areas, information is transferred while using the first dynamic address and the second dynamic address corresponding to the respective service areas as a header. It is, therefore, possible to considerably decrease the probability of momentary disconnection during hand-over.